“Supermalaria” Is on the Way
There has been growing hope in recent years that malaria could eventually be eradicated but that sense of optimism is currently facing some major new challenges. Scientists are warning that a “supermalaria” parasite is spreading rapidly across Southeast Asia, and could pose a global health threat if it spreads to Africa. It is resistant to artemisinin, the recommended first-line treatment for malaria. In addition, if the U.S. Congress carries out the proposed 44 percent cut to the President’s Malaria initiative (PMI) funding, it could have a significantly undercut prevention and treatment programs. Projections show that the PMI cut alone could lead to an additional 300,000 malaria deaths over the next four years.
Although the disease continues to be a major global public health problem, the number of deaths from malaria has been falling due to the impact of major PMI-funded control programs, which include insecticide-treated bed nets, indoor residual spraying and anti-malarial treatments. In 2015, there were an estimated 438,000 malaria deaths worldwide compared to 584,000 in 2013. The majority (92 percent ) of these deaths have been in sub-Saharan Africa and it is feared that if the drug-resistant strain currently seen in Southeast Asia spreads to Africa, it could diminish the gains that have been made.
Unfortunately, the sudden emergence and spread of this new resistant strain should not come as a surprise to malaria control experts—it’s a case of history repeating itself. Just like insecticide resistance, drug resistance is a phenomenon that we have experienced before, and will probably see again and again until malaria is eventually eradicated. Thus, we should view the periodic emergence and re-emergence of drug resistance as an opportunity to learn something new about the malaria parasite and its transmission, develop even more sustainable ways of controlling it, and make any new, alternative treatments last longer. Even more important, we need to redouble our efforts to increase and maintain funding for malaria control.
The rapid spread of resistant parasites is fueled by Anopheles mosquitoes (when they bite humans parasites are passed between different hosts) and the rise in globalization with the increase in air travel across continents. The current frontline tools for malaria control—including treatment using artemisinin combination therapy, sleeping under insecticide-treated nets (ITNs) and indoor residual spraying (IRS)—are effective, but the persistence of malaria transmission points to gaps in current practice. Closing these gaps requires a deliberate effort to sustain and improve the gains made and, I would argue, for the establishment of an agenda that promotes a more integrated approach to malaria control.
The goal of malaria eradication is a constantly moving target. Malaria parasites and the mosquitoes that transmit them are continuously changing in response to control measures, and so keeping pace requires dynamism in approach and practise and shifting our focus towards encouraging multiple, concurrent strategies against the parasite and the mosquito. Control also needs to be linked to the communities themselves; environmental and community health workers can draw important lessons from the successes of integrated pest management in agriculture.
Malaria involves the human host, the mosquito vector and the parasite. As the parasite life cycle occurs partly in the mosquito and partly in the human host, this naturally presents two avenues through which malaria control is currently focused; first, to reduce human-vector contact through the increased use of ITNs and IRS and, second, to control parasite circulation in the human population through surveillance and effective treatment of identified cases.
Whilst some benefits of these frontline interventions are already being realized, I believe that integrating these with other control measures in a multidisciplinary approach will ultimately provide the added impact that is likely to shrink the existing gaps and push the eradication agenda forward. An example of these other control measures is the elimination of mosquito breeding habitats as part of an integrated vector management(IVM) framework that includes active community participation to enhance sustainability. Another important control measure is the development of clearly defined tools for community health workers to facilitate the monitoring of malaria patients following effective diagnosis and timely treatment.
A good example of where this has been effective is in Sri Lanka, where the disease was eliminated. The Sri Lankan antimalaria program has been successful—even in spite of regular movement of people between the island and India and 20 years of war and political unrest—because of a multi-dimensional approach. It had an effective mosquito control program, a three-pronged parasite surveillance program, and “patient management” or treatment of the disease. The big question remains whether a similar approach can be developed in malaria endemic regions of sub-Saharan Africa. The prospects are high as the tools applied in Sri Lanka are available; what is now needed is a well coordinated implementation step supported by advocacy, political will and adequate funding. Thus the proposed PMI funding cuts are only likely to make worse an already bad situation. They should be reconsidered.
The fears that the “supermalaria” parasite in Southeast Asia could spread to Africa are justified. So in addition to ensuring integrated malaria control locally, this is the time to also put a greater emphasis on pre-travel advice and chemoprevention, especially to people traveling between Africa and Asia. When resistance to an antimalarial first emerges, it does so in non-immune people. These are usually indigenous infants and young children who are yet to acquire immunity (which comes from surviving repeated malaria attacks), or adult foreign visitors to endemic areas. This could be the perfect opportunity for the World Health Organization and other stakeholders in malaria control to strengthen existing regulations and introduce new rules governing the use of malaria prophylaxis among international travelers, similar to the mandatory vaccinations for diseases such as yellow fever.
The malaria research community has a great sense of commitment to exploring ways of controlling the disease and mustn’t be despondent even in the face of supermalaria. It might take a lot of time, work and funding to tackle this new challenge but we have more experience and knowledge than ever before. However, to keep the hope of malaria eradication in our sights, we must apply the lessons learnt over the decades of successful malaria control to halt the spread of this super parasite and avert a crisis. It might be a new battle to face, but it doesn’t mean that we have lost the war.
Janet Midega is a scientist at the KEMRI-Wellcome Trust Research Program in Kilifi, Kenya, a research associate at the University of Oxford’s Center for Genomics and Global Health, and a 2017 Aspen New Voices Fellow.